A rotary die equipped with a blade is used for perforating a work, such as paper, to facilitate separation, or for punching or stamping. FIGS. 14 and 15 show a rotary die block 100 and a rotary anvil 200 used in association with the rotary die block 100. The die blade 1 has a cutting edge 12 which is curved along the contour of the die block, and projected beyond its periphery so as to penetrate a work (W) such as paper or metal sheet.
By referring to FIGS. 14 and 15, the conventional rotary die unit will be described:
A work (W) such as paper or metal sheet is passed between the rotary die 100 equipped with a die blade 1 and the rotary anvil 200 in the direction (F) indicated by the arrow. While passing therebetween, the work (W) is subjected to perforating or slitting or stamping operations as desired by the blade 1. The rotary anvil 200 has two kinds; one having a hard surface as of iron, and the other having a soft surface made as of rubber, depending upon the nature of the work (W).
The blade 1 fixed to the rotary die block 100 has two kinds; one is obtained by curving a straight strip shown in FIG. 16, and shaping it on the user's side as shown in FIG. 17, and the other is obtained by procuring a previously curved blade commercially available. In the latter case, it will be very handy if the obtained blade has a curvature as desired, and in the former case, the blade can be curved on the user's side to a desired curvature, where, as shown in FIG. 17, three rollers 301, 302 and 303 are employed with one being inside and the other two outside. Each of the rollers 302 and 303 is provided with a groove on its rim so as to support the edge 12 in a non-contact manner. This method is disclosed in Japanese Patent Publication No. 46 (1971)-18352.
The problem arises from the latter case shown in FIG. 19, in the form of the betrayal of the expectations of handiness and readiness because of the difficulty in selecting a curvature agreeable to the desired value. The problem of the former case shown in FIG. 17 is that parts (A) are likely to remain unprocessed because of the structural limitation inherent in the illustrated type of machine. These unprocessed parts (A) must be removed by an extra process, thereby increasing the production cost.
Therefore, an object of the present invention is to provide a method and apparatus for obtaining rotary die blades conformable to the contour of the die block throughou its full length.
Another object of the present invention is to provide a method and apparatus for variously shaping the edge of the die blade as the user desires.
A further object of the present invention is to provide a method and apparatus for ensuring the conformity of the die blade to the contour of the rotary die block without requiring a special skill.
A still further object of the present invention is to provide a method and apparatus for ensuring the conformity of the die blade to the contour of the rotary die block under a computer control.